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Flashcards in Cell Cycle + Replication Deck (38):
1

Mitosis Promoting Factor (MPF)

Present in the cytoplasm of M cells

Induces mitosis

Activates protein kinase

2

Why is MPF found in all eukaryotes?

it is highly conserved and essential for promoting mitosis

3

Cyclin dependent kinase

an enzyme that catalyzes the transfer of a phosphate group

from ATP to a target protein

4

Phospholyzation

the transfer of ATP to a target protein

catalyzed by protein kinase

target proteins need energy input to begin mitosis

5

What happens when more cyclin is present?

MPF concentrations in the cytoplasm rise

target proteins are phospholyzed which initates mitosis

6

When do MPF concentrations peak?

During M phase

7

When do MPF concentrations rise?

During interphase

8

What is the MPF composed of?

Cyclin and cyclin-dependent kinase bound together

9

Cyclin

a regulatory protein that fluctuates in order to initiate M phase

it attaches to cdk's to form MPF

therefore, when cyclin rises, MPF rises

10

Concentration of cdk's

remain constant

only cyclin fluctuates since cdk's are hard to reproduce

11

How many cyclin/cdk combos are there?

There are many combos that regulate the cell cycle for each phase

12

G1 checkpoint

pass if cell size is adaquent, DNA is undamaged, nutrients are sufficient

13

G0

mature cells do not pass the G1 checkpoint and enter into the G0 phase

14

G2 checkpoint

pass if DNA is undamaged and has replicated successfully

activated MPF is present

15

M checkpoint

chromosomes attatched to spindle apparatus

chromosomes have properly segregated and MPF is absent

16

When do checkpoints occur?

At the end of phases

Make sure work supposedly to be done in certain phases is complete

17

origin of replication

replication bubbles form at specific sequences of bases

18

How many origins of replications do bacteria have?

Only one

That this why their DNA is circular

19

How many origins of replications do eukaryotes have?

Many

Speeds up replication

20

Where does active DNA synthesis take place?

At the replication fork

21

Replication fork

Y-shaped region where the parental DNA double helix is separated into single strands and copied

22

What direction does DNA have to be copied in?

5' to 3'

23

Why is DNA synthesis bidirectional?

2 replication forks going in both directions at the same time

24

Helicase

breaks the hydrogen bonds between base pairs and opens the double helix at the replication fork

25

Single-stranded DNA binding proteins

prevent the separated DNA strands from snapping back into place

26

topiomerase

an enzyme that prevents supercoiling of DNA

27

primer

an RNA strand that forms complimentary base pairs with the DNA template strand

provides DNA polymerase with a 3' -OH group that can be used to form phosphodiester bonds

28

Leading strand

strand that is synthesized toward the replication fork

synthesized continuously

29

Lagging strand

synthesized in a direction that is away from the moving replication fork

synthesized in short Okazaki fragments

has to readjust to go in 5' to 3' direction

30

Primase

synthesizes a short stretch of RNA that works as a primer

31

DNA polymerase I

removes the RNA primer and replaces it with DNA

32

the end replication problem

there is no primer for DNA

33

telomere

protective end of chromosomes

TTAGG strand that is okay to loose due to end replication problem

34

Is DNA polymerase bidirectional?

No. It is unidirectional

35

Ligase

connects the fragments with phosphodiester bonds

works on BOTH the leading and lagging strands

36

How does telomerase work?

it extends the unreplicated end of DNA

lays down a primer and following the primer TTAGG cap

DNA is replicated to primer and the TTAGG cap is lost behind it, but that is alright

37

When are telomeres added in the cell cycle?

during the S phase

38

When are telomeres created?

During pre-natal development

born with all the telomeres we get

as we age, DNA becomes shorter